The present invention relates to a manufacturing method and device of a board having a fine circuit pattern such as a semiconductor device or a liquid crystal and more particularly to a pattern inspection art of a semiconductor device and a photo mask such as a pattern inspection art on a wafer during the semiconductor device manufacturing process and a comparison inspection art using an electron beam.
Inspection of a semiconductor wafer will be explained as an example.
A semiconductor device is manufactured by repeating the step of transferring a pattern formed on a photo mask onto a semiconductor wafer by the lithographic process and etching process. In the semiconductor device manufacturing process, acceptance or rejection of the lithographic process, etching process, and others and an occurrence of a foreign substance greatly affect the yield rate of semiconductor devices, so that to detect an error or failure generation early or beforehand, the method for inspecting a pattern on a semiconductor wafer in the manufacturing process has been conventionally executed.
As a method for inspecting a defect existing in a pattern on a semiconductor wafer, a defect inspection device for irradiating white light to a semiconductor wafer and comparing the same kind of circuit patterns of a plurality of LSIs using an optical image is in practical use and the outline of the inspection method is described in xe2x80x9cMonthly Semiconductor Worldxe2x80x9d, August issue, 1995, pp 96 to 99. As an inspection method using an optical image, a method for imaging an optically irradiated area on a board by a time delay integration sensor and detecting a defect by comparing the image with a preinput design characteristic is disclosed in Japanese Patent Application Laid-Open 3-167456 and a method for monitoring image deterioration at the time of image acquisition and correcting it at the time of image detection and thereby executing a comparison inspection using a stable optical image is disclosed in Japanese Patent Publication 6-58220. When a semiconductor wafer in the manufacturing process is inspected by such an optical inspection system, pattern remains and defects having a silicon oxide film or photosensitive resist material on the surface through which light transmits cannot be detected. Etching remains and an unopened failure of the minute contact hole lower than the resolution of the optical system cannot be detected. Furthermore, a defect generated at the step bottom of the line pattern cannot be detected.
As mentioned above, as refinement of the circuit pattern, complication of the circuit pattern shape, and diversification of the material advance, defect detection by an optical image becomes difficult, so that a method for comparing and inspecting the circuit pattern using an electron beam image having a higher resolution than that of an optical image is proposed. When the circuit pattern is to be compared and inspected by an electron beam image, to obtain a practical inspection time, it is necessary to obtain an image at a very higher speed than that of observation by a scanning electron microscope (hereinafter abbreviated to SEM). It is also necessary to ensure the resolution of the image obtained at high speed and the SN ratio of the image.
As a pattern comparison inspection device using an electron beam, in J. Vac. Sci., Tech. B, Vol. 9, No. 6, pp 3005 to 3009 (1991), J. Vac. Sci., Tech. B, Vol. 10, No. 6, pp 2804 to 2808 (1992), Japanese Patent Application Laid-Open 5-258703, and U.S. Pat. No. 5,502,306, a method for irradiating an electron beam having an electron beam current 100 times or more (10 nA or more) of that of a normal SEM to a conductive board (X-ray mask, etc.), detecting any of generated secondary electrons, reflected electrons, and transmitted electrons, and comparing and inspecting images formed from the signal and thereby automatically detecting a defect is disclosed.
As a method for inspecting or observing a circuit board having an insulator by an electron beam, in Japanese Patent Application Laid-Open 59-155941 and Electron, Ion Beam Handbook (Nikkan Kogyo Shimbunsha), pp 622 and 623, a method for obtaining a stable image by irradiating a low velocity electron beam of 2 keV or less so as to reduce the effect of charging is disclosed. Furthermore, in Japanese Patent Application Laid-Open 2-15546, a method for irradiating ions from the back of a semiconductor board is disclosed and in Japanese Patent Application Laid-Open 6-338280, a method for canceling charging an insulator by irradiating light to the surface of a semiconductor board is disclosed.
By a large current and low velocity electron beam, it is difficult to obtain an image with high resolution due to the space charge effect. However, as a method for solving it, in Japanese Patent Application Laid-Open 5-258703, a method for decelerating a high velocity electron beam immediately before a sample and irradiating it practically as a low velocity electron beam on the sample is disclosed.
As a method for obtaining an electron beam image at high speed, a method for obtaining an electron beam image by continuously irradiating an electron beam on a semiconductor wafer on a sample carrier by continuously moving the sample carrier is disclosed in Japanese Patent Application Laid-Open 59-160948 and Japanese Patent Application Laid-Open 5-258703. As a secondary electron detection device used in a conventional SEM, a constitution of a scintillator (aluminum deposited phosphor), a light guide, and a photoelectric multiplier is used. However, this kind of detection device detects light emitted from the phosphor, so that the frequency responsibility is bad and the detection device is not suited to high-speed formation of an electron beam image. To solve this problem, as a detection device for detecting a secondary electron signal of high frequency, a detection means using a semiconductor detector is disclosed in Japanese Patent Application Laid-Open 5-258703. Furthermore, an art for scanning an electron beam at the same location on a semiconductor wafer on a sample carrier once or several times at high speed by continuously moving the sample carrier, obtaining an image at high speed, and automatically inspecting a defect by image comparison is disclosed in Japanese Patent Application Laid-Open 10-294345.
When the circuit pattern in the manufacturing process of a semiconductor device having a minute structure is inspected using the aforementioned optical inspection system of the prior art, remains of a silicon oxide film which is an optically transmissive material and whose optical distance depending on the optical wave length and refractive index used for inspection is sufficiently small and a photosensitve resist material cannot be detected and it is difficult to detect etching remains whose linear short width is smaller than the resolution and an unopened failure of the minute contact hole.
On the other hand, in observation and inspection using an SEM, the conventional electron beam image forming method using an SEM requires an extremely long time, so that inspection of the circuit pattern overall a semiconductor wafer requires an extremely long time. Therefore, to obtain a practical throughput in the semiconductor device manufacturing process, it is necessary to obtain an electron beam image at a very high speed, ensure the S/N ratio of an electron beam image obtained at high speed, and maintain the predetermined accuracy. When the material constituting the circuit pattern to be inspected is formed by an insulating material such as a photo resist or a silicon oxide film and formed by coexistence of an insulating material and a conductive material, it is difficult to obtain an image of stable brightness by inspection by an electron beam and obtain the predetermined inspection accuracy. The reason is that when an electron beam is irradiated to a substance, secondary electrons are generated from the portion, but since the irradiated current is not equal to the secondary electron current, when the inspection object is an insulator, it is charged, and the secondary electron generation efficiency from the portion and the trajectory of secondary electrons after generation are adversely affected, and the contrast of an image is changed, and the image is not reflected by the actual circuit pattern shape and distorted at the same time. This charging state is sensitive to the electron beam irradiation condition and when the electron beam irradiation speed and irradiation range are changed, even the same circuit pattern at the same location becomes an image having an exactly different contrast. As a result, depending on a combination of a material to be inspected or the shape and others, there is a case that the contrast necessary to recognize the existence of a defect cannot be obtained from the obtained image.
As described in the aforementioned prior art, to detect a defect which cannot be detected by the optical inspection method, as a method for irradiating an electron beam to a conductive board, obtaining an electron beam image, and comparing and inspecting it, a method for irradiating and inspecting an electron beam narrowly limited to a sample board at high speed is disclosed in Japanese Patent Application Laid-Open 59-160948 and Japanese Patent Application Laid-Open 5-258703. However, in this prior art, a method for adjusting inspection conditions for a material such as an insulator, the shape of a pattern to be inspected, and a defect to be detected is not described. In Japanese Patent Application Laid-Open 59-155941 which is another prior art, to observe a board having an insulator, a method for decelerating a primary electron beam to be irradiated to the sample board and reducing the irradiation energy, for example, to 2 kev or less is described. However, this prior art is a method for continuously irradiating an electron beam to a certain local area and obtaining an image after the charging of this local area is stabilized and it is not suited to inspect a wide area at high speed because it requires a long time to obtain an electron beam image. Furthermore, even if the charging in the local area is stabilized, it is difficult to control another area to be compared to the same charging state and for example, it is difficult to inspect a wide area such as a semiconductor wafer. In Japanese Patent Application Laid-Open 10-294345, a method for irradiating a large current electron beam to a circuit pattern to be inspected only once, detecting a signal at high speed in the state before the contrast is changed, thereby equalizing the charging state of a wide area, and obtaining an electron beam image with a stable contrast is disclosed. In this prior art, the degree of charging varies with a material, so that a method for adjusting the irradiation energy of an electron beam irradiated to a sample by adjusting the negative potential applied to the sample and sample carrier is described. However, in this prior art, there is no concrete description on setting the shape and material of a pattern to be inspected and irradiation conditions of an electron beam to a defect to be detected.
Namely, in an inspection method and inspection device for forming an image at high speed by scanning a large-current electron beam to a sample at high speed as mentioned above and detecting a defect by the image process, the image quality is different from that of a normal SEM. There is little contour information and the pattern shape and existence of a defect must be discriminated by the contrast by the material and shape. Therefore, when the pattern portion on the surface and the lower layer are not contrasted, the pattern portion cannot be recognized and as a result, it is difficult to detect a defect of the pattern. A failure such as a conduction failure of a hole pattern or a short failure between neighboring independent transistors can be recognized as a contrast different from that of a normal pattern by the potential contrast caused by the difference in the charging state of the sample surface when an electron beam is irradiated. However, depending on irradiation conditions of an electron beam, there is a case that no difference is caused in the contrast between the normal area and the defective area and detection of a defective portion is difficult.
Therefore, depending on the kind of a circuit pattern to be inspected and the step to be inspected, the material, shape, step, and kind of a defect to be detected are changed and the contrast characteristic of an electron beam image is different between the material, shape, step, and kind of defect, so that it is necessary to obtain respective optimum electron beam irradiation conditions beforehand as conditions at the time of inspection.
An object of the present invention is to provide an inspection method and inspection device for inspecting a semiconductor circuit pattern using an electron beam image, wherein by obtaining a contrast trend beforehand and storing it as a device parameter, there is no need to search for electron beam irradiation conditions suited to inspection for various inspection circuit patterns each time.
Another object of the present invention is to reduce the time for searching for optimum electron beam irradiation conditions whenever inspection conditions of a circuit pattern to be inspected, that is, an inspection recipe is to be set by accomplishing the aforementioned first object.
Still another object of the present invention is to provide an art for promptly corresponding to inspection of all circuit patterns to be inspected by accomplishing the aforementioned first and second objects.
A further object of the present invention is to enhance the sensitivity for detecting various defects in various circuit patterns by accomplishing the aforementioned first to third objects.
A still further object of the present invention is to provide a device wherein optimum electron beam irradiation conditions are presented according to the aforementioned circuit patterns and the conditions are set as inspection condition parameters and built as a data base so that conditions can be set optionally and to accomplish the aforementioned first to fourth objects. Yet a further object of the present invention is to solve the aforementioned first to fifth problems, provide an art for inspecting a circuit pattern with high precision and in high sensitivity according to a circuit pattern to be inspected, and provide an inspection method for reflecting the inspection results in the manufacturing conditions of semiconductors and others by applying the inspection to a minute circuit pattern of a semiconductor device and others and contributing to enhancing the reliability of semiconductor devices and others and also reducing the failure rate.
A board having a minute circuit pattern such as a semiconductor device and others is formed by combining various conductive layers and insulating layers. The structure of a circuit pattern varies with the function and specification of the circuit. When the material and structure are different, the process of manufacturing a circuit pattern and the manufacturing device to be used are different, so that the contents of a defect generated are also different. Furthermore, when the size of a circuit pattern is different, the allowance of the manufacturing process is different, so that the easiness of occurrence of a defect is different. As described in Japanese Patent Application Laid-Open 10-294345, when the inspection is executed using an inspection method and inspection device for irradiating a large-current electron beam to a board having a minute circuit pattern at high speed, obtaining an electron beam image by detecting a signal instantaneously, and comparing it with the neighboring equal pattern, to accomplish the above object of detecting a defect in high sensitivity under the optimum inspection condition respectively according to such various circuit patterns, the inspection method and inspection device of a circuit pattern relating to the present invention will be described hereunder.
To inspect a circuit pattern at high speed, it is necessary to irradiate a large-current electron beam once or several times, detect generated secondary electrons for an extremely short time, thereby form an electron beam image. When such a large-current electron beam is used, the electron beam on a sample will be a thick electron beam having a diameter of 50 nm to 100 nm or so compared with a diameter of 3 nm to 10 nm of a normal SEM. The examination of the inventor shows that than an electron beam image by the contour information of the shape obtained by a narrowly limited electron beam like the aforementioned normal SEM, an electron beam image of the contrast generated by the secondary electron generation efficiency of the material of a sample is more suited to detection of a defect. The secondary electron generation efficiency varies with the material of the lower layer and surface pattern forming the circuit pattern and the layer thickness, so that when an electron beam image having a large brightness contrast of the pattern and lower layer caused by this material is obtained, a defect of the pattern or lower layer can be easily detected. When an electron beam image is formed at high speed using such a thick large-current electron beam of about 50 nm to 100 nm in diameter, it is found that the image quality is different from that of a normal SEM. This difference will be described hereunder.
Firstly, when a small-current electron beam narrowly limited to 3 nm to 10 nm is slowly irradiated to a sample and a signal is detected for many hours, an electron beam image by the contour information of the shape is obtained. On the other hand, when a thick electron beam of about 50 nm to 100 nm in diameter described in the prior art of Japanese Patent Application Laid-Open 10-294345 mentioned above is irradiated to a sample at high speed and an image is obtained instantaneously, an electron beam image of the contrast caused by the secondary electron generation efficiency of the material of the sample and the detection efficiency is obtained. As described already, since the electron beam diameter is larger than that of the SEM, how to see the shape contour is different from that of a normal SEM. Since an electron beam is scanned in a wide area at high speed, that is, the scanning width of the electron beam is wide, the magnification of an image, that is, the pixel size is different from that of a normal SEM. Furthermore, since a signal is detected at high speed immediately after the electron beam is irradiated and an image is formed, the charging state on the sample surface is different. Furthermore, since a constitution that a negative potential is applied to the sample and sample carrier is used, the potential state on the sample surface is different. As a result, when a large-current electron beam is scanned at high speed, and a signal is detected at high speed, and an image is formed, the inventor finds that an image quality different from that of a normal SEM is obtained.
The brightness of an electron beam image varies with the material of the uppermost surface of a circuit pattern to be inspected, pattern shape, and step. When an electron beam image is obtained under the same electron beam irradiation condition, it is found that no contrast is obtained depending on a combination of the materials of the pattern and lower layer and it is difficult to detect a defect from such an image. It is also found that the contrast is changed depending on the pattern step and shape. The secondary electron generation efficiency of each of the materials constituting the circuit pattern varies with the charging state. Therefore, when the charging condition under which the brightness contrast is increased by the materials of the surface pattern and lower layer is optimized by the materials, an electron beam image suited to detect respective defects in correspondence to a combination of various materials can be formed. To change the contrast, it is effective to change the charging state of a sample. However, when the scanning speed of an electron beam and the irradiation count to the same location are changed, for example, when the irradiation count to the same location is assumed as 8 times, the inspection time is increased to 8 times. Even when the scanning speed of an electron beam is changed, the inspection time is also adversely affected. When the electron beam current is reduced so as to narrowly limit the electron beam, the S/N ratio of an image is decreased and defect detection becomes difficult. As a method for changing the charging state without the inspection time being adversely affected, by changing the electron beam irradiation energy condition according to the material and shape of a circuit pattern to be inspected, step, and contents of a defect to be detected, it is found that the charging state of the sample surface is changed without the inspection time and S/N ratio of an electron beam image being adversely affected and the contrast suited to defect detection can be obtained. The contents of examination for realizing such an inspection will be described hereunder.
The first means realizes that by controlling and changing the electron beam irradiation energy and changing the sample charging state which varies with the material, even if the combination of materials is different, a brightness contrast is obtained. The control of the electron beam energy to be irradiated to a sample is made possible by the following means. A primary electron beam generated from the electron source is set to the desired acceleration voltage and the electron beam passes through the optical path at this acceleration voltage. When the acceleration voltage of the primary electron beam generated from the electron source is changed, the deflections of various lenses which are set midway in the optical path and the conditions of the electrode and coil current are all changed greatly and it is necessary to readjust the optical axis each time of changing. When the irradiation energy is to be changed according to the shape and material of a circuit pattern to be inspected and a defect to be detected, the irradiation energy must be changed frequently and frequent great adjustment of the optical axis is troublesome, so that it is not desirable for keeping the optical conditions of the electron beam stable. Therefore, a constitution is used that by applying a negative potential to a sample or the sample carrier, the acceleration energy of the primary electron beam is reduced right above the sample and the electron beam is irradiated to the sample by the irradiation energy after deceleration. Since the degree of deceleration can be changed by variably controlling this negative applied voltage, the irradiation energy to a sample can be set optionally. Since the electron beam advances up to right above the sample at the fixed acceleration voltage, there is no need to greatly adjust the optical axis midway in the path and it is sufficient to finely adjust the effect of deceleration on the surface electric field.
The second means realizes that when the negative potential is to be applied to the sample or sample carrier by the first means, the adjustment of the lenses for focusing the voltage and current of the deflecting electrode and the electron beam on the sample in link motion with it is built as a data base as device parameters and other device parameters can be automatically set according to the voltage to be applied to the sample or sample carrier. By doing this, no optical axis adjustment is executed, and the parameters to be input by a user are minimized, and appropriate device conditions can be set automatically.
The third means decides the potential to be applied to a sample or sample carrier according to the material of the uppermost surface of a circuit pattern to be inspected. When there are a plurality of materials existing on the surface to be irradiated by an electron beam, the potential to be applied to the sample or sample carrier is decided by a combination of the materials. Although detailed conditions will be described in embodiments, for example, when a photosensitive resist is on a conductive layer, a conductor and an insulator are combined, so that an area having a comparatively low acceleration voltage where the potential contrast is discriminated is desirable. Since a photo resist is apt to be charged, the potential of 2 kV to 3 kV at which a photo resist is easily charged is not desirable. When a silicon oxide film and a silicon nitride layer are combined, both are insulating materials, so that unless the charging state is changed, no contract can be obtained. Therefore, in such a case, the potential of about 3 kV is desirable. As mentioned above, there is appropriated electron beam irradiation energy according to each of the materials. When these electron beam irradiation conditions are built as a data base in correspondence to a combination of materials and the material kind and for example, recommendation conditions of the inspection mode having a photo resist are presented when the inspection conditions are set, appropriate inspection conditions can be set unless detailed conditions are searched for each circuit pattern to be inspected.
The fourth means decides the potential to be applied to a sample or sample carrier according to the kind of a defect to be detected on a circuit pattern to be inspected. When there are a plurality of kinds of defects to be detected, the potential to be applied to the sample or sample carrier is decided by a combination of the defects. Although detailed conditions will be described in embodiments, for example, when a non contact failure of the contact hole connecting the board and capacitor is to be detected on a circuit pattern forming a transistor, the comparatively low potential of 1 kV or less suited to discrimination of the potential contrast is desirable. However, when the step of a pattern to be inspected is large and a defect of the pattern shape generated in the step bottom is to be detected, the comparatively high potential of 3 kV or higher at which an electron beam can easily reach the step bottom is desirable. As mentioned above, the appropriate electron beam irradiation energy is different according to the kind of a defect to be detected. In the same way as with the third means, when these electron beam irradiation conditions are built as a data base and for example, the recommended value of the shape defect detection mode is presented, appropriate inspection conditions can be set easily without detailed inspection conditions being searched for each time.
The fifth means realizes searching of inspection conditions from the information of the aforementioned circuit pattern to be inspected when an inspection condition file is to be created from the operation screen. When an inspection condition file is to be created, conventionally, the arrangement of circuit patterns, the size of chips (die) in them, and the layout of the memory cell, peripheral circuit, and test pattern are input and the image processing conditions for deciding a defect are input. However, in addition to it, for example, selection of materials such as xe2x80x9cphoto resist modexe2x80x9d, xe2x80x9cline material (conductive layer material) modexe2x80x9d, and xe2x80x9cinsulating material/insulating material modexe2x80x9d, selection of xe2x80x9chigh step modexe2x80x9d, xe2x80x9clow step modexe2x80x9d, and xe2x80x9cno-step modexe2x80x9d, and selection of the kind of a defect to be detected such as xe2x80x9cpotential contrast defect detection modexe2x80x9d, xe2x80x9cshape defect detection modexe2x80x9d, and xe2x80x9cpotential contrast/shape defect composite detection modexe2x80x9d are carried out from the menu on the screen, and the recommended value of the potential to be applied to a sample or sample carrier is presented by a combination of these selections, and the electron beam irradiation energy is decided from the beginning by the recommended value, and then various arrangements and the brightness of an image are adjusted and the defect decision conditions to be obtained from an image are decided, thereby an electron beam image is always formed under the electron beam irradiation condition most suitable for a pattern to be inspected and the defect inspection can be executed using the electron beam image. The recommended values for the aforementioned various patterns are obtained beforehand as device parameters, built as a data base in correspondence to the aforementioned inspection modes, and registered as one of the items of the inspection condition data base. The contents of various optimum conditions will be described in detail in embodiments.
By each of the means mentioned above, optimum electron beam irradiation energy can be set according to a circuit pattern to be inspected and a contrast which is stable and suited to the image process can be obtained. A means for detecting a defect generated on a circuit pattern from an electron beam image will be described hereunder. The first area of a sample is irradiated by a first electron beam, and secondary electrons generated from the sample surface are detected highly efficiently at high speed, and an electron beam image signal is obtained in the first area of a board to be inspected and stored in the first storage. In the same way, an electron beam image is obtained in the second area of the sample having an equal circuit pattern to that of the first area and stored in the second storage, and the detailed position adjustment is executed for the images in the first and second areas by the image processor, and then a differential image is obtained by comparing the images in the first and second areas, and a pixel that the absolute value of the brightness of the differential image is more than a certain predetermined threshold value is decided as a defect candidate. Under the same electron beam irradiation condition as the conventional one, a contrast may be obtained or may not be obtained depending on the kinds of a material and a defect. When no contrast is obtained, it is difficult to adjust the decision of defect detection and the difference in brightness cannot be extracted easily. Therefore, when a defect is extracted by the aforementioned means using an electron beam image having a large contrast always stably under the electron beam irradiation condition, a defect can be detected in higher sensitivity.
By executing the aforementioned inspection method, an inspection method and an inspection device for inspecting a circuit pattern on a board including various shapes, materials, and defects by an electron beam highly sensitively at high speed and automatically detecting a defect generated on the circuit pattern can be realized.
By the aforementioned various means, according to the detailed pattern shape and material of a wafer to be inspected, conditions of irradiation light and detection conditions thereof, image comparison conditions, defect decision conditions, and others are set respectively, and when these conditions are to be appropriately changed whenever the process conditions of a semiconductor device are changed, the recommended value of inspection condition corresponding to a circuit pattern to be inspected is registered as an inspection mode beforehand, and a user selects the condition corresponding to the circuit pattern to be inspected from the inspection mode, thereby optimum electron beam irradiation conditions can be set automatically, so that an inspection condition file can be simply input according to the predetermined procedure and the efficiency is improved.
Furthermore, in setting of the electron beam irradiation energy, the potential to be applied to a sample or a sample carrier and conditions of various lenses affected by it and of the deflection electrode are also set as device parameters in link motion, so that the user can set inspection conditions without setting various complicated parameters. Since it is sufficient only to change the irradiation energy to the sample, the inspection time and S/N ratio of an image will not be adversely affected.
As a result, to a semiconductor device for various products and steps, a highly precise inspection can be applied early and also the potential mistaking the contents and numerical value of an input parameter is reduced. As a result, even an operator who is not trained specially can set optimum inspection conditions simply. Therefore, using the aforementioned inspection method and device constitution, by obtaining an image of a circuit pattern and comparing and inspecting it, various device parameters for automatically detecting a defect generated on the pattern can be set simply.
Using the method and device, by inspecting a board having a circuit pattern, for example, a semiconductor device in the manufacturing process, in a semiconductor device in each of the steps, a shape failure or defect of the pattern caused by the processing, which cannot be detected by the prior art, can be detected early and as a result, problems latent in the process or manufacturing device conditions can be discriminated. By doing this, the causes of failures in the manufacturing process of various boards such as a high-speed and highly precise semiconductor device compared with conventional devices can be removed and a high yield rate, that is, a high acceptance rate can be ensured and the maldetection generated during inspection which is questionable is reduced at the same time, so that a highly precise inspection can be executed. In a semiconductor device of various kinds of products and various kinds of steps, the setting of inspection parameters for which the prior art requires an extensive time can be executed efficiently in a short time and as a result, the desired appearance inspection can be applied early to the desired products and steps and the condition setting will not adversely affect processing completion of a wafer used for condition setting. As a result, details of a pattern shape failure caused by the processing and fine foreign substances can be confirmed early and the TAT from detection of an failure occurrence to a countermeasure can be shortened.
In the inspection method of the present invention, as a step of setting electron beam irradiation conditions according to a circuit pattern to be inspected, any or all of the electron beam irradiation energy to a sample, electron beam current, and electron beam irradiation count to the same area are set.
Furthermore, as a step of setting electron beam irradiation conditions according to a circuit pattern to be inspected, various inspection conditions including electron beam irradiation conditions are built, set, and stored as a data base beforehand and the inspection condition data base is read at the time of inspection execution.
The electron beam irradiation energy to a sample is set by a negative voltage applied to the sample and sample carrier.
The electron beam current is set by the voltage of the electrode and the current of the coil which are provided in the electronic optical system.
The electron beam irradiation conditions are set according to the material of a circuit pattern to be inspected, and the inspection conditions are set according to the pattern step of the circuit pattern to be inspected, and the electron beam irradiation conditions are set according to the pattern size and pattern shape of the circuit pattern to be inspected, and the electron beam irradiation conditions are set according to the kind of a defect to be detected on the circuit pattern to be inspected.
When the material of the surface of a circuit pattern to be inspected is a photosensitive resist, the electron beam irradiation energy is set within the range from 300 V to 3 kV, preferably from 1.5 kV to 3 kV after photo resist development, 1.5 kV to 3 kV after etching, or from 0.3 kV to 0.5 kV after conductive material filling.
When the surface material of a circuit pattern to be inspected is a combination of an insulating material and a conductive layer, the electron beam irradiation energy is set within the range from 300 V to 5 kV, preferably from 1 kV to 3 kV.
When the surface material of a circuit pattern to be inspected is a combination of an insulating material and a different insulating material, the electron beam irradiation energy is set within the range from 1.5 kV to 5 kV, preferably from 1.5 kV to 3 kV.
When the step of a circuit pattern to be inspected is 0.3 xcexcm or more, the electron beam irradiation energy is set within the range from 1.5 kV to 5 kV, preferably in the neighborhood of 3 kV.
When the step of a circuit pattern to be inspected is less than 0.3 xcexcm, the electron beam irradiation energy is set within the range from 300 V to 3 kV, preferably within the range from 0.5 kV to 0.8 kV.
When the kind of a defect to be detected on a circuit pattern to be inspected is a non-conduction failure of the contact hole, the electron beam irradiation energy is set within the range from 300 V to 3 kV, preferably within the range from 0.5 kV to 0.8 kV.
When the kind of a defect to be detected on a circuit pattern to be inspected is a short failure of the transistors or lines, the electron beam irradiation energy is set within the range from 300 V to 3 kV, preferably within the range from 0.5 kV to 0.8 kV.
When the kind of a defect to be detected on a circuit pattern to be inspected is a pattern shape failure, the electron beam irradiation energy is set within the range from 1 kV to 5 kV, preferably within the range from 1 kV to 3 kV.
When the kind of a defect to be detected on a circuit pattern to be inspected is thin film remains, the electron beam irradiation energy is set within the range from 300 V to 3 kV, preferably in the neighborhood of 0.5 kV.
When the kind of a defect to be detected on a circuit pattern to be inspected is all of a contact hole failure, a shot failure of the transistors or lines, and a pattern shape failure, the electron beam irradiation energy is set within the range from 1 kV to 5 kV, preferably within the range from 1 kV to 3 kV.
When the pattern shape of a circuit pattern to be inspected is a contact hole and the step that the inside of the hole is filled with a conductor is to be inspected, the electron beam irradiation energy is set within the range from 300 V to 3 kV.
When the pattern shape of a circuit pattern to be inspected is a contact hole and the step that the inside of the hole is not filled, the electron beam irradiation energy is set within the range from 800 V to 5 kV.